For the cake (I doubled this recipe to get four 9-inch round layers):

Preheat oven to 400F. Sift together 2 cups sugar, 2 cups flour, and 1 teaspoon cinnamon. In a saucepan, mix 4 tablespoons cocoa and 1 cup water. Add 2 sticks margarine or butter and bring to a boil. Pour this into the flour mixture and blend well. (Do not use an electric mixer; blend by hand.)

Mix together 1/2 cup buttermilk, 2 beaten eggs, 1 teaspoon baking soda, and 1 teaspoon vanilla. Add to the batter and blend well. Pour into greased and floured pans. Bake at 400F for 20 minutes or until cake tests done. Completely cool cake on wire racks before frosting.

For the chocolate cream cheese frosting for between the layers:

Combine powdered sugar, cream cheese, butter, and cocoa. Add vanilla. Add heavy whipping cream a few tablespoons at a time while mixing until desired consistency. Use to assemble the cake, frosting between each layer, for a total of 3 layers of frosting.

For the dark chocolate ganache for the top and sides of the cake:

In a saucepan, mix and bring to a simmer the whipping cream and butter. Add the chocolate chips and stir until smooth. Let sit until completely cool. (I actually let it cool completely and then put it in the refrigerator for a bit, just to make sure it has a pretty thick consistency.) Frost the top and sides of the cake, licking the bowl often!